In the blow molding of conventional bottles, most of the top face of the neck is open to permit easy pouring of the contents of the bottle. The open portion is surrounded by a flat flange, adjacent and perpendicular to the threaded sidewall of the neck, and this flange is used as a sealing surface for the underside of a threaded or crimped bottle cap. Many methods familiar to practitioners of the blow molding process are known for the formation of these neck openings and flanges.
However, it is sometimes advantageous to form a molded recess extending from the top face of the neck and within the outer neck diameter, and to provide an opening within this recess through which to dispense the contents of the bottle. Referring to the attached figures, FIG. 1 shows a perspective view of such a bottle design. More specifically, FIG. 2 shows in section the neck and surrounding area of the bottle. The outer neck diameter 10 abuts a top flange 11 which in turn encircles a center recess 12 consisting of side walls 13, a bottom wall 14, and a dispensing hole 15 through the bottom wall 14. An example of such a construction is a bottle containing a liquid cleaner or protective coating which must be dispensed through an applicator attached to a cleaning or coating machine. In the example illustrated in FIG. 2, the center recess 12 retains a circular rubber gasket 16 with a hole through its center generally matching the hole 15 in the bottom wall 14 of the center recess 12.
The bottle as shipped from the filler is typically closed by a screw cap (not shown), the underside of which seals off against flange 11. The user of the fluid in the bottle removes and sets aside the screw cap. He or she then affixes the bottle to the applicator tool, shown in section in FIG. 3, by twisting the bottle neck onto bayonet joint projections 17 molded on the inner sides 18 of the bottle neck receiving recess 19 of the applicator. Gasket 16 then engages and seals against a metering hub assembly 20 in the recess 19.
Until the present time it has not been possible to mold such a bottle without a secondary operation. One choice has been to drill or punch the center hole after molding, increasing cost and introducing chips or other contamination into the bottle. An equally undesirable alternative has been to mold the center recess section separately and to attach it to the inner surface of the bottle neck, also increasing cost and introducing the risk of leakage.
What is desired, therefore, is a method and apparatus for blow molding bottles having a hole formed in a molded interior recess extending from the top face of the bottle neck in which the complete neck and recess portion of the bottle, including the dispensing hole, are formed as a single operation during the molding cycle.